This must be a calla lily

This is the bloom of my mystery plant.

Garden Tasks for Early Summer (June)

Preparations

• Feed flowering shrubs and roses with a rose fertilizer to promote flowering.
• Weed carefully to avoid damage to nearby plants.
• Buy bedding plants and plant out after the last frost.

Planting

• Plant hanging baskets and summer pots outside when all risk of frost is past.
• Plant out half-hardy and tender bedding plants after the last frost.

Pruning

• Prune late spring-flowering shrubs and climbers after they have bloomed.
• Trim vigorously growing hedges, like privet.

Other Tasks

• Remove suckers from roses.
• Tie in climbers regularly to their supports.
• Divide congested clumps of primulas and irises after they have flowered.
• Continue to take softwood cuttings.
• Mow lawns regularly and lower the blades.
• Water new plants in dry spells.

This list was found in Learn to Garden: A Practical Introduction to Gardening.  I did modify the list a little.   

Am I overwatering/underwatering???

My lilies are yellowing then browning.  Below are pics.  What is the cause??

In Bloom

My lilies have bloomed!  I probably have some other colors too, but the bulbs are too small for flowering this year.

Not sure what variety...

Asiatic Lily "Cancun"

Asiatic Lily "Tango Passion Ladylike" (I believe)

Daylily, Hemerocallis fulva